The present invention relates to a process for the continuous fluorination of carbon, and more particularly to a process for preparing a fluorinated carbon such as poly(carbonmonofluoride) or poly(dicarbonmonofluoride) by contact reaction of carbon with a fluorine gas. The present invention also relates to an apparatus for solid-gas reaction wherein the reaction of a solid and a gas is efficiently conducted without accumulating the reaction heat.
Recently, a fluorinated carbon has been watched as a new industrial material, and has been applied to various uses, for instance, as an active material for primary cells of high energy density, as a solid lubricant contained in liquid lubricants, greases and coating compositions, and as a fluorinating agent. Therefore, the demand for the fluorinated carbon has increased and a process for the preparation thereof suited for the mass production has been desired.
Hitherto, there have been adopted a batch process in which the reaction is carried out by passing a fluorine gas diluted with an inert gas through carbon particles placed in a reactor without any forced transference and the reaction product is taken out from the reactor after the completion of the reaction; and a continuous process in which the reaction is carried out by passing a fluorine gas diluted with an inert gas through carbon particles which are being transferred in a rotary kiln.
However, the batch process has the defect that the production capacity per bed area of a reactor is low and the production efficiency is bad. When the reactor is charged with a large quantity of carbon particles in order to raise the production efficiency, in other words, when the carbon particles are put on a bed of the reactor in a thick layer, the reaction heat is remarkably accumulated, since the thermal conductivities of the starting carbon particles and the produced fluorinated carbon are low and the reaction heat is not efficiently removed. Therefore, the thermal control is conducted with difficulty during the reaction, and as a result, degradation of the fluorinated carbon frequently takes place in the course of the reaction. When the carbon particles are put on the bed in a thin layer, much labor and time are required, thus lowering the production efficiency, though the accumulation of the reaction heat is avoided. Also, in the batch process, the contact efficiency is very inferior.
The continuous process using a rotary kiln can eliminate the problem of the batch process in taking the particles in and out. However, the heat efficiency is bad, and the heat removal is also bad because of an effective area of heat transfer being small. Moreover, uniform mixing of the particles is insufficient. The process also has the disadvantages that the reactor per a unit production amount is large and useless spaces are many, and the structure of the reactor is complicated.